Method of filling containers with explosive mixtures



Oct. 2, 1945. N. M. HOPKINS METHOD OF FILLING CONTAINERS WITH EXPLOSIVEMIXTURES File-d March 9, 1942 INVENTOR ORNEY Patented Oct. 2, 1945STATES METHOD OF FILLING CONTAINERS WITH EXPLOSIVE MIXTURES ApplicationMarch 9, 1942, Serial No. 433,988

7 Claims.

This invention pertains to the practically perfect and safe making of afluid explosive, one safer to package, ship, store and use after makingand packaging, than such explosives as dynamite or nitroglycerin, forexample.

It is an object of this invention, therefore, to provide not onlypractically perfect safety in the making and packaging of an explosive,but to produce a packaged explosive as an article of manufacture, saferto ship, store, and use than dynamite or nitroglycerin, for example.

It is a particular object of this invention to package, with the highestdegree of safety to life, limb and property, nitrogen tetraoxide and oneor more liquid, semi-liquid, or solid combustible bodies, benzol,ordinary gasolene, high octane gasolene, kerosene, carbon-disulphide,turpentine, certain heavy greases, and certain finely dividedcombustible solids and the like, to use as a substantially safeexplosive cartridge or cannister as compared to such explosives asdynamite and nitroglycerin, for example.

It is also a special object of thisinvention to institute a greaterelement of safety than heretofore to life, limb and property in thepreparation of the explosive as in the preparation of nitroglycerin anddynamite, due to the fact that the explosive herein described is notproduced until after it has been packaged and the mechanical process ofhermetic sealing has been completed.

Liquid nitrogen tetraoxide, when mixed with a liquid combustible bodyvsuch as benzol, for example, enters into a mutual solution therewith, noconventional chemical reaction with the evolution of heat taking placeas in the case of nitrating glycerin, for example; therefore all thepotential energy present in the component parts of the explosive ispackaged for the blast at the field of use. In nitrating glycerin, thereacting masses must be kept cool by running water and naturally manythermal units of energy are discarded in the process of manufacture.Since there are no comparable thermal units thrown away in making a meremutual solution of liquid nitrogen tetraoxide and benzol, for example,applicant asks the question, Why throw away at the factory what you wishto use in the field? In order to adequately introduce this subject,setting forth thereby the needs for the new products proposed, a briefrsum of the characteristics of two liquid, and several solid explosivesis given, and applicants reasons, who has been engaged in explosives,for over forty years, wherein they all fail in connection withindustrial and military use.

Nitroglycerin is too sensitive to shock and therefore too dangerous.Furthermore if nitroglycerin leaks out of a" container it may formdangerous pools or puddles, which is not the case with cartridges andcannisters using liquid nitrogen tetraoxide as one of the componentparts. Moreover, nitroglycerin has far too great a shattering power forsome purposes, and freezes, at 131 C. or 555 F.a comparatively hightemperature. Moreover, nitroglycerin is a dangerous compound to thaw outwhen frozen. In addition, it causes severe headache when it comes incontact with the skin.

Dynamite is also too sensitive to shock and likewise too dangerous for.most industrial purposes, and is not favored for any military or navalpurposes, not only because it is easily frozen, since it has anitroglycerin content and is dangerous to thaw out, but it is readilydetonated by a comparatively light shock, and usually by the impact of arifie bullet. Moreover, the safe storage period for dynamite is limited.

Liquid oxygen is applied as an explosive in mines when mixed withcharcoal where prompt firing of the charge is possible. The liquidoxygen must be transported to the mines in open vessels, the liquidboilingoff continually and therefore always at considerable loss, sinceliquid oxygen cannot be confined practicably by hermetic sealing. Liquidair explosives, however, possess a very desirable safety factor, due tothe very fact that after a period of time, if a charge is not fired, itboils away, and leaves a harmless deposit of carbonaceous materialbehind. Thus many accidents which occur with dynamite which has failedto explode in a bore hole and subsequently accidentally detonated, areavoided. Due to the fact, however, that liquid oxygen cannot behermetically sealed, its use as an oxidant as a component part of anexplosive mixture is very limited.

Ammonium nitrate dynamite is manufactured under a number of formulas andtrade names, and contains usually from 20 to 30 per cent nitroglycerin.It is quite hygroscopic, and is too dangerous for most purposes,especially military demolition work, as it is also detonated by theimpact of certain rifle bullets or flying shell fragments.

Ammonal is another ammonium nitrate explosive, very hygroscopicand'lacks proper shattering power for many purposes. I

Ammonium picrate is far too insensitive for blasting and militarydemolition Work, since it requires an expensive high shock boosterdetonation to set it off.

Blasting gelatin is made according to a variety of formulas. Itoccasions very severe headaches when it comes into contact with thehands of the human body, and is again too sensitive to shock for manypurposes.

Picric acid is a nitrated phenol and is an ill and uncertain explosive]It becomes wet in the atmosphere and is set off when in this conditionwith great difficulty. It is crumbly and porous, and not only stains theskin and clothing, but it forms dangerously sensitive salts when incon-' tact with certain metals. The nitration process is a roundaboutand uneconomic one.

Gun cotton has to be kept wet to prevent it from undergoing chemicalchange and in becoming too sensitive. When it is wet it requires dry guncotton, or an equivalent high-power booster, to cause its detonation.

Nitrostarch more or less recently developed for demolition purposes, bythe military engineers, is not very stable and accelerated stabilitytests, as well as long periods of storage, have not shown it to bewholly reliable. It is quite hygroscopic and not very effective inproducing induced detonation.

T. N. T. is far too expensive for industrial blasting and in addition itrequires a high power booster detonator to set it off. It has beenstandardized practically the world over for military and naval purposes,but is dependent upon toluene, a commodity which may become verydifficult to procure in large enough quantities during a prolonged majorWar.

Amatol is a mixture of T. N. T. and ammonium nitrate and althoughsomewhat cheaper than T. N. T. is still too expensive for industrialblast-v ing purposes.

With the foregoing enumerated objects in View, as well as certain otherobjects which will become apparent as the description proceeds and thedrawings are studied, the invention consists in the improvements overthe prior art as partially listed above, and consists in the novel partsand principles, methods, ways and means, as well as physical states ofmatter, all as herein set forth, and particularly pointed out in theclaims.

Referring to the accompanying drawing forming a part of thisspecification, in which like numerals designate like parts in all theviews:

Fig. 1 is a sectional view through one design of one of my completedarticles of manufacture, comprising an explosive cannister with acapsupported well-way, showing in elevation an electrical detonatortherein positioned to fire the cannister-contained explosive charge.

Fig. 2 is a sectional view through one design of one of my articles ofmanufacture, showing alternate detail plans for a detonator well-way,and recess, respectively, and one of the liquid component parts of theliquid explosive in the liquid state, and another of the liquidcomponent parts of the said liquid explosive in the frozen solid state.

Fig. 3 represents one design of one of my double-safe and easily ventedcartridges, comparable in size and shape to a conventional dynamitecartridge. The contained component parts of the liquid explosive areadjusted for a given sensitivity in strength, with one of the liquidcomponent parts of the liquid explosive, namely the nitrogen tetraoxide,frozen solid as evidenced by the oblique cross hatching .ofcomparativelywidely separated lines.

Fig. 4 represents a similar design of one of my cartridges with one ofthe liquid component parts of the liquid explosive, namely the nitrogentetraoxide, frozen solid as evidenced by the oblique cross hatching ofcomparatively widely separated lines, this cartridge havin a greatersensitivity in strength over that illustrated in Figure 3.

Referring to Fig. l 20 is a cannister wall of sheet iron, sheet tinnediron, sheet steel, or aluminum, for example, of definite guage andthickness, and of definite characteristics as to hardness and thickness,for example, 2| indicating a bottom member, either integral with theside walls of the cannister as by deep drawing, or attached by one ofthe standard mechanical closure methods in can manufacture with a gasand liquid tight juncture, and 22 is a cap member, mechanically appliedto the top of the cannister to make a pressure resisting, as well as agas and liquid tight, fit. The cap may be of the wellknown crown cap andseal variety, such as is used on beer, gingerale and charged waterbottles, in which case the lip member 23 of the neck 24 must be crimpedor beaded to receive it, no attempt being made in the drawing to showthe wellknown corrugated elements of such a crown cap and seal. In theplace of the crown cap, I may of course elect to use a threaded cap anda threaded neck member, using the inexpensive rolled threads, forexample, or make a soldered cap closure, using a pure tin or leadfreesolder, since liquid nitrogen tetraoxide attacks lead but does notattack tin at all ordinary temperatures. I may in the top of this capmember 22 bore a countersink, 290, thereby reducing the thickness of themetal there so that it may be easily punctured, by a needle-pointedbradawl, in order that vapor from the surface 380 of the mixed liquidexplosive 56 may escape, and in due time, a time which may be adjustablewith temperature, and thus render the explosive cannister harmless, ifthe charge is not fired Within an adjusted or specified time.

Here supported from the cap member 22 is a detcnator well-way 25, eithera deep drawn and integral part of the cap, or mechanically attached witha pressure resisting gas and liquid tight joint. 26 illustrates inelevation an electric detonator, and 21 and 28 are insulated electricwires connected to a heating bridge wire within the detonator casing andadjacent to the fulminating mercury or other explosive'capable, of beingexploded by heat. Here 50 is an explosive mixture of liquid nitrogentetraoxideand one or more combustible bodies, benzene, gasolene,especially high octane gasolene for anti-freeze purposes, kerosene,carbon disulphide, heavy grease, heavy grease incorporated with finelydivided carbonaceous matter, or the like. This explosive mutual solutionor mixture, or both, may be one of many, ranging from one consisting of20 per cent liquid nitrogen tetraoxidelto per cent of benzol by volume,for example, to one consisting of '70 per cent liquid nitrogentetraoxide to 30 per cent benzol by volume, for example, the exactproportions of such mixtures being dictated by sensitivity or power todo work requirements.

In Fig. 2 in a wall of the cannister 28 is shown an alternate well-wayor recess 31 for the reception of a detonator and the'additionalalternate well-way 25' integral with, as by deep drawing, ormechanically and hermetically attached against internal pressure to thebottom or closure member 2|. In this view a simple closure cap 22' hasbeen forced upon the bead 23 said simple cap being bored part waythrough at 200 in order that a pointed bradawl may easily perforate themetal over the gas chamber formed by the neck of the cannister above theliquid level 388. In the place of the simple crown cap of course asimple screw cap or other suitable closure system may be mechanically,as well as hermetically, applied. In the filling operation, a volume ofliquid nitrogen tetraoxide is supplied to the interior of the can, andthen frozen therein, as indicated by the cross hatched lines at M], andthis freezing operation may be carried out by im-' mersing the cannisterin a suitable freezing mix ture, or by immersing the cannister in atrough of flowing brine, said brine being an element of a mechanicalrefrigerating system. Since liquid nitrogen tetraoxide freezes at minusten degrees Centigrade or 14 degrees Fahrenheit, to a mass of colorlesscrystals, there is no difiiculty at all in not only freezing the liquidgas to a solid, but in super-cooling the frozen mass. Here 38 is avolume of refrigerated benzol, or a volume of refrigerated benzol towhich a freezing point depressant has been added, some high octanegasolene for example, so that the benzol will not freeze above thetemperature of the liquid nitrogen tetraoxide, but be liquid at the sametemperature, or lower. This to prevent the melting of the solid frozennitrogen tetraoxide and consequent mixing with the benzol, and therebymaking a partial or complete explosive mixture therewith, untilcompletion of the mechanical process of forcing on, or screwing on, orsoldering, or other wise attaching the cap member 22.

By this novel means of filling the cannister with nitrogen tetraoxideand one or more liquid comb-ustible bodies, the said nitrogen tetraoxidebeing in frozen state to prevent its admixture with the liquid body, Iinsure the highest order of safety in packaging to life, limb andproperty, no matter how roughly the cannister is handled or how sharplythe cap member may be forced on by hand, by semi-automatic, or byautomatic machinery. In the present illustration, it will be evidentthat upon thawing out the frozen component of the fluid explosive, thatwe will have substantially a 50-50 mixture by volume of the liquidnitrogen tetraoxide and the liquid hydrocarbon or hydrocarbonsrespectively.

In the new filling process involving this principle for the highestorder of safety, I plan to advance step by step a plurality of my openmouthed cartridges or cannisters suitably supported upon a moving belt,said moving belt advancing step by step while immersed in a trough oi.refrigerated brine, said brine being at a temperature well below thefreezing point of liquid nitrogen tetraoxide. During the step by stepprocess the cartridge cases or cannisters are passed successively undersuitable nozzles leading to refrigerated, but not frozen, supplies ofliquid nitrogen tetraoxide and liquid or fluid ccmbustible substancesrespectively. At refrigerating temperatures of just above the freezingpoint of liquid nitrogen tetraoxide, the liquid gas is docile and easilyand safely handled, a suitable exhaust fan system being neverthelessinstalled to carry on and discharge out of doors anynitrogen-tetraoxide-vapor-contaminated atmosphere. After the canm'stershave been filled to the required depth, according to the sensitivity andpower of the explosive desired, and the said liquid nitrogen tetraoxidefrozen solid, the refrigerated benzol,

gasolene, or mixture of benzol'and high octane gasolene, for example, isthen admitted through suitable nozzles to fill the cartridges orcannisters except for a suitable liquid-free space to serve as a gaschamber as indicated in the drawing.

After the addition of the refrigerated liquid hydrocarbon or hydrocarbonmixture, the cartridges or cannisters are passed under theca-papplyingmechanism. With continuous indication of brine temperature by suitablerecording thermometers taken in connection with the time of immersion ofthe cartridges or cannisters in the brine during their advancementsthrough the brine in the filling process, we may always know that one orall of the component parts'of the liquid explosive are frozen solid andmoreover that the liquid nitrogen tetraoxide, because of its freezingpoint, was frozen first, and therefore there would be the minimum ofdanger'to life,

limb, and property under the capping machinery.

It is not deemed necessary to illustrate here the complete intermittentmotor drive of the endless conveyor belt nor the details of the troughand the immersion of the belt therein, nor the measuring devices at thefilling nozzles, nor any of the other numerous details necessary andstandardized in more or less analogous automatic filling systems, thefilling of beer cans and bottles with beer, for example.

Coming now to Fig. 3, there is shown at 60 a simplified cap member'witha drawn well-way SI for the reception of the firing detonator and aminiature drawn well-way 6| one drawn by dies fashioned to produce athin and easily punctured bottom. Both of thesewell-ways projectdownward from the cap member 60, which is attached to an end 62 of theiron, tinned iron, teel or aluminum shell 63, by screw threads andgasket (not shown), by a drive fit and soldering using lead-freetinsolder, by rolling on, by welding, or any other pressure resisting andgas tight method or ways and. means.

Here the miniature well-way 6| has a thinned bottom member 200' oneeasily punctured by a bradawl with needle point, which puncture upon theremoval of the bradawl allows the vapor of the liquid nitrogentetraoxide at the surface level 350' to escape. I may elect to supplythe interior Of this. miniature well-way 6| with a standardizedneedle-point 40!! attached to a small friction-guiding spider 500, saidneedle point being ground upon a shaft which extends slightly above thecap 60 and terminates in a button 600 fashioned to be depressed by thethumb of the operator. By standardizing the thickness of the metal at26c and the ogive and diameter of the steel needle for puncturing, I maybe able to calibrate for definite periods of time for the completeescape of the liquid nitrogen tetraoxide after puncturing the bottom end20B of the well-way 6| when the cartridges are at the temperature ofmelting ice, for example, easily attained by putting a dozen or more ofthese new blasting cartridges in a bucket of ice and water.

By means of this method it will be evident that these cartridges may berendered safe within substantially the same period of time in eithersummer or winter. Where numerous holes have been drilled in rock or-madein soil, for exam ple, and a plurality of cartridges are planted for ablast, only one of the cartridges being fired by a detonator, itfrequently happens that all of the cartridges are not fired bysympathetic -detonation, in which case, with ordinary dynamitecartridges, serious accidents tolife and limb may subsequently resultfrom an unfired cartridge. With the present cartridge, if one or moreshould fail to fire by sympathetic detonation, they will be renderedharmless aftera preadjustment period of time, because the liquidnitrogen tetraoxide'will boil away, its vapor passing through thecalibrated hole made by the needle in the metal bottom 200' of thewell-way 6|. The cartridge shown at Fig. 3 has a bottom closure member64 attached to the end 65 of the shell 63, the attachment being madepressure resisting and gas and liquid tight.

Here, as in the case of the cannisters of the previous figures, 40 is amass of frozen nitrogen tetraoxide, and 30 a volume of a refrigeratedliquid hydrocarbon or a mixture of refrigerated liquid hydrocarbons, orother combustible material with a temperature as low as or lower thanthe temperature of the frozen solid nitrogen tetraoxide. Here we have asubstantially 50-50 volume respectively of the combustible material andthe solid frozen liquid gas, capped and sealed hermetic-ally before thefrozen solid liquid gas has had time to melt and mix with the liquidcombustible material. This 50 50 mixture of chemically controlledingredients, when they are both in the fluid state, may be testedaccording to applicants standardized kinetic energy impacts.

In Fig. 4 there is shown substantially the same structure as in Figure3, only a different distribution of frozen liquid nitrogen tetraoxideand liquid combustible material, a mixture more sensitive to shock andalso one more powerful when exploded, since high sensitivity and highpower go largely hand in hand in the present liquid explosive. Thecartridge casing here as before has been hermetically closed before themelting of the frozen nitrogen tetraoxide 40, thereby eliminating alldanger to life, limb and property.

Though this invention has been particularly described in the foregoingas adaptable to explosive cartridges containing a liquid mixture ofnitrogen tetraoxide and a combustible body such as a hydrocarbon(benzene-for example), it is quite obvious that the invention is capableof application, in a broader sense, to an hermetically sealed containerhaving therein a plurality of any ingredients (constituting a mixture)one of which ingredients is of such a character as would be vaporized,chemically changed, or actually ignited and/or exploded by thetemperature necessary. to complete the hermetic sealing of thecontainer, and hence some of the claims have been directed to cover suchbroader aspect of the invention. a

It is obvious that those skilled in the arts may vary the steps andcombinations of steps constituting the novel method herein describedwithout departing from the spirit of this invention, wherefore it isdesired not to be limited to the exact foregoing disclosure except asmay be required by the claims.

What is claimed is:

1. The method of filling a container with two liquid ingredients whichcomprises introducing one (of the ingredients in aliquid phase thereofinto the container, freezing the introduced liquid ingredient while inthe container, introducing the other ingredient in aliquid phase thereofinto the container and in contact with the'frozen ingredient,hermetically sealing the container before the frozen ingredient hasmelted, and liquefying the frozen ingredient after the container issealed.

3. The method of producing an explosive cartridge consisting of acontainer and a mixture therein of ingredients each separatelyrelatively insensitive to explosion but forming a sensitive explosivemixture when admixed, which comprises disposing in the container one ofthe ingredients in a solid phase thereof, introducing the otheringredient in a liquid phase thereof into the container and in contactwith the solid ingredient, maintaining the two ingredients in theirrelatively insensitive respective solid and liquid phases whilehermetically sealing the container, and liquefying the solid phaseingredient after the container is sealed to bring about the admixture ofboth ingredients.

3. The method of producing an explosive cartridge consisting of acontainer and a mixture therein of liquid ingredients each separatelyrelatively insensitive to explosion but forming a sensitive explosivemixture when admixed, which comprises introducing into and solidlyfreezing one of the liquid ingredients in the container, adding theother liquid ingredient to the solidly frozen ingredient in thecontainer, maintaining the two ingredients in their relativelyinsensitive respective solid and liquid phases while hermeticallysealing the container, and liquefying the solid'phase ingredient afterthe container is sealed to bring about the admixture of bothingredients. I

4. The method of safely producing an explosive cartridge consisting of acontainer and a mixture therein of liquid ingredients each separatelyincapable of explosion but forming a sensitive explosive mixture whenadmixed, which comprises introducing into and solidly freezing liquidnitrogen tetraoxide in the container, adding a liquid hydrocarbon to thesolidly frozen ingredient in the container, maintaining the twoingredients in their respective solid and liquid phases whilehermetically sealing the container, and liquefying the solid phaseingredient after the container is sealed to bring about the admixture ofboth ingredients.

5. The method of producing an explosive cartridge consisting of acontainer and a mixture therein of liquid ingredients each separatelyrelatively insensitive to explosion but forming a sensitive explosivemixture when admixed, which comprises introducing into and solidlyfreezing one of the liquid ingredients in the container, adding theother liquid ingredient to the solidly frozen ingredient in thecontainer, the such addition being at a temperature at least as low asthe temperature of the frozen ingredient, maintaining the twoingredients in their relatively insensitive respective solid and liquidphases while hermetically sealing the container, and liquefying thesolid phase ingredient after the container is sealed to bring about theadmixture of both ingredients.

6. The method of producing an explosive cartridge consisting of acontainer and a mixture therein of liquid ingredients each separatelyincapable of explosion but forming a sensitive explosive mixture whenadmixed, which comprises introducing into and solidly freezing liquidnitrogen tetraoxide in the container, adding a liquid hydrocarbon to thesolidly frozen ingredient in the container, the ingredients being in therelative proportion of 60% by volume of liquid nitrogen tetraoxide to40% by volume of liquid hydrocarbon, maintaining the two ingredients intheir respective solid and liquid phases while hermetically sealing thecontainer, and liquefying the solid phase ingredient after the containeris sealed to bring about the admixture of both ingredients.

7. The method of producing an explosive cartridge consisting of acontainer and a mixture therein of liquid ingredients each separatelyincapable of explosion but forming a sensitive explosive mixture whenadmixed, whichcomprises introducing into and freezing liquid nitrogentetraoxide in the container, adding a. liquid hydrocarbon to the solidlyfrozen ingredient in 10 the container, the ingredients being in therelative proportion of 30%-'70% by volume of liquid nitrogen tetraoxideto 70%-30% by volume of liquid hydrocarbon, maintaining the twoingredients in their respective solid and liquid phases whilehermetically sealing the container, and liquefying the solid phaseingredient after the container is sealed to bring about the admixture ofboth ingredients.

NEVIL MONROE HOPKINS.

